I’m suggesting a distinction between two ways of doing the history of philosophy: as a spectator, and as a conversational partner. There is a continuum between those extremes. I’ll focus on the extremes.
(1) The spectator way: a kind of history of philosophy that focuses, or tends to focus, on exegesis and on determining the bottom line of a philosopher’s views; this with some but not much effort to formulate the philosophical problems that lead them to those views, the philosophical difficulties of dealing with those problems, and even their arguments: that is, without much attempt to re-think what the philosopher thought, and get inside the internal debate they had with other views and with themselves, without letting oneself feel the philosophical temptations they were battling, and therefore also without trying to overcome those temptations. This way of doing the history of philosophy may describe the historical process, but typically very little of the thought process, that lead the philosopher to the endorsement of some view. At the end of such historical discussions one may feel that one knows what the philosopher thought, but not so much why. This way of doing the history of philosophy typically involves comparisons of the philosopher’s views with some more or less immediate influences on them, typically comparisons of formulations of the views of the philosopher with formulations of similar or contrasting views by other thinkers that the philosopher read or was in contact with. But this form of doing the history of philosophy will typically not be so much concerned with placing the philosopher’s ideas in a broader historical context. Mention might be made of more distant philosophers, but again, the focus will typically be on specific formulations of views, rather than on re-creating the philosophical difficulties temptations and tendencies the philosopher struggled against.
My description here can be used as a mere caricature, but also to capture a form of degeneration that sometimes happens in the work of historians of philosophy (although this may not be taken as a form of degeneration).
(2) The conversational partner way: a kind of history of philosophy that focuses first and foremost on understanding and sharing the philosopher’s problems, understanding how those problems arise, and what philosophical temptations they give rise to, perhaps re-formulating and re-generating those problems in a more accessible language (sometimes running the risk of anachronism). Typically, it involves the belief that there is not really knowing what the philosopher thought without knowing why they thought that. Doing the history of philosophy in this way involves active engagement in a process of debating and making up one’s mind about a philosophical issue, and not just about correctly identifying what a philosopher thought. It involves a discussion of the philosopher’s ways of thinking and methods which attempts to reveal how their methods fit the philosophical problems they were engaged with, and it may involve testing those methods, perhaps attempting to bring these methods and ways of thinking to bear on other problems—even problems the philosopher did not deal with explicitly. When commenting on specific points in the philosopher's thought, the conversational-partner historian of philosophy might occasionally engage in the activity of the spectator as described above—mere exegesis, identifying the what without the why, etc.—but when they do, and if this is all they do, this will typically involve a sense of failure, either the philosopher's or the historian's, or a sense that when it comes to that specific point, the philosopher's view is not very important philosophically.
Part of the reason for suggesting this distinction is that it might explain why some currentists—philosophers who do not take themselves to do the history of philosophy—deny the importance of the history of philosophy: If the history of philosophy is done in the first way I mentioned, and if in this way the ideas of a philosopher get “trapped” in their time-period, and are not allowed to be re-generated, thought anew, grow beyond their time-period, or be in a conversation with ideas from other time-periods, then it is not a huge surprise that some, or even many, would think it is not very relevant to what they are doing, and so dismiss it.
Another part of the reason for this suggestion is that it applies to currentist philosophy as well: Discussions of current ideas may equally be “trapped” in their time-period. It will feel less artificial and trapped, because this time-period is current and the discussions fashionable, but it will not be less problematic. If true, this suggests there is a way of doing current philosophy in a way that is responsive to the history of philosophy (and to its future).
Furthermore, I described the first way of doing philosophy, whether the history of philosophy or current philosophy, as trapped in a time period. But I want to go further. This first way of doing philosophy is trapped, but not in a certain conversation. Rather, it avoids a certain philosophical discussion—discussion of philosophical problems and temptations, attempting to make up one’s mind about a philosophical question—and is in this sense not involved in a philosophical conversation at all. In this sense, this way of doing philosophy is trapped out of philosophy. At its worse, it comes down to philosophizing by finding a place for a view on a map of possible views; it gives rise to the sport of identifying new possible positions on the map. It promotes philosophical wackiness. It comes to: ‘You think that, I think this,’ or ‘There are several possible views here…,’ and that’s it; that’s the whole conversation—a conversation of placing views side by side, without identifying any friction between them, without showing the connections, the ways of moving from one to the other, how one view is a response to problems with other views, etc. In the second, historically open, way of doing philosophy, the philosophical conversation is much more robust.
So the distinction I am suggesting is also between “historically trapped” ways of doing philosophy (whether trapped in the past or the present), and historically “open” ways. And my claim is that doing the history of philosophy in the second way described above and doing current philosophy in the second way I hypothesized, is really very similar: They involve participating in, or at least openness to, the same conversation. Philosophers who do the history of philosophy and philosophers who do current philosophy in these ways will not think of themselves as doing different things.